It is desirable to establish a three-dimensional [3D] surface profile of a region of interest shown in such images, e.g., to enable 3D motion tracking of the region of interest.
US 2010/0149315 A1 describes an imaging system and method for colposcopic imaging in which three-dimensional (3D) imaging information is combined with motion tracking information. The system includes at least one structured light source for projecting a structured light pattern on the portion of an object and at least one camera for imaging the portion of the object and the structured light pattern. It is said that the structured light source projects the structured light pattern onto the imaged object for generating feature points, measures the feature points, and uses them for reconstructing the 3D surface topology of the imaged object. It is further said that the structured light sources may include a laser light source for generating a laser beam, a holographic grating for diffracting the laser beam, and one or more reflective surfaces for directing the diffracted laser beam.
A problem of the imaging system of US 2010/0149315 A1 is that it is complex as it requires the use of different types of light sources during the colposcopic imaging to enable reconstructing the 3D surface topology of the imaged object.
DE102010009884 A1 discloses an endoscope inserted into the body cavity, wherein a region of the inner surface is illuminated from different directions, one after another in time, by means of at least three light sources. The light sources are spaced apart from each other on or in the endoscope. Using a camera one image is recorded in respect of each of the illuminated region from the same camera position, so that, for a plurality of object points of the region, said associated image points comprise the same image coordinates for each of said object points in each of the three images, one after another in time. Information about the three-dimensional structure of the region is derived from the intensities of the image points in each of the images.
US2005/0254720 A1 describes a method to enhance an output image of a 3D object. A set of input images are acquired of a 3D object. Each one of the input images is illuminated by a different one of a set of lights placed at different positions with respect to the 3D object. Boundaries of shadows are detected in the set of input images by comparing the set of input images. The boundaries of shadows that are closer to a direction of the set of lights are marked as depth edge pixels.
DE19532095 C1 discloses an endoscope having a tube with a lens set into the tip that focuses the image of the observed object into a fibre optic conductor that has a further lens directing the image onto a video camera. The tip section has lighting output groups positioned on opposite sides and at the ends of conductors. The image is obtained with alternating lighting from the two groups and this creates a recorded image having a stereoscopic effect.
In-vivo images including three-dimensional or surface orientation information may be captured and viewed. EP1326432 A2 describes an in-vivo site being illuminated by a plurality of sources, and the resulting reflected images may be used to provide three-dimensional or surface orientation information on the in-vivo site. The system may include a swallowable capsule.
The above referred prior arts do not refer to illuminating the region of interest together with identifying the insufficiently illuminated region and providing a solution to overcome the insufficient illumination of the region of interest.